NASA’s DART Mission Reshapes Target Asteroid, Reveals Loose ‘Rubble-Pile’ Composition
In a groundbreaking discovery, scientists have found that the target asteroid of NASA’s Double Asteroid Redirection Test (DART) may have been reshaped by the impact. The investigation into the aftermath of the collision has revealed that the asteroid, known as Dimorphos, exhibits a loose “rubble-pile” composition. This finding has significant implications for our understanding of asteroids and their potential threat to Earth.
The DART mission, which took place on September 26, 2023, involved slamming a spacecraft into the moonlet Dimorphos, which orbits a larger space rock called Didymos. The aim of this mission was to test whether a kinetic impact could alter the trajectory of an asteroid and potentially prevent a collision with Earth in the future. Six months after the impact, NASA confirmed that the mission had been successful, with Dimorphos’ orbit around Didymos reduced by 33 minutes.
Now, new research led by University of Bern scientist Sabina Raducan has shed light on the composition and shape of Dimorphos. Using state-of-the-art computer modeling, the team determined that Dimorphos is a loose, rubble-pile asteroid. This suggests that the moonlet may have formed from material that was ejected from its larger asteroid partner, Didymos.
Before the DART mission, scientists were unsure of what to expect from Dimorphos. Raducan explains, “Because the system is so far away from Earth, Dimorphos was not properly resolved. Therefore, we could have encountered anything from a monolithic body to a cohesionless rubble pile or anything in between.” The impact outcome came as a surprise to most, but it was one of the predicted scenarios.
Furthermore, the research shows that Dimorphos has a very different composition from other asteroids like Ryugu and Bennu, but their reaction to impacts was surprisingly similar. The team’s simulations also indicate that the DART collision completely reshaped Dimorphos through a process called global deformation. This reshaping caused the exterior of the moonlet to be resurfaced with material from its interior.
The simulations revealed that around 0.5% to 1% of Dimorphos’ mass was ejected as a result of the impact, while 8% of its mass was redistributed. This significant reshaping and resurfacing of the asteroid suggests that the internal composition and distribution of materials greatly influence the structural integrity and response to impacts of small asteroids.
These findings not only provide valuable insights into the Dimorphos and Didymos asteroid system but also contribute to our understanding of other binary asteroids in the solar system. Raducan explains, “The material properties and structure of Dimorphos as derived in this study suggest the small moon likely formed through rotational mass shedding and re-accumulation from Didymos.” This knowledge enhances our understanding of the formation and evolution of similar binary systems in our solar system.
The primary aim of the DART mission was to test planetary defense methods, and it has certainly delivered on that front. Raducan states that these results will inform the development of future asteroid exploration missions and guide the design of planetary defense initiatives. The kinetic impactor technique used in the DART mission has proven to be an effective deflection mechanism for small, rubble-pile asteroids like Dimorphos.
However, Raducan emphasizes the importance of conducting reconnaissance missions before attempting deflection. Accurately assessing an asteroid’s properties is crucial in determining the most appropriate deflection strategy. The upcoming European Space Agency (ESA) Hera mission will provide valuable data to validate and refine the models created by Raducan’s team.
In conclusion, the DART mission has not only reshaped our understanding of asteroids but also demonstrated the effectiveness of kinetic impactors in deflecting potential threats. The research conducted by Raducan and her team has provided valuable insights into the composition, structure, and dynamics of asteroids. These findings will undoubtedly contribute to our ongoing efforts to protect Earth from potential asteroid collisions.
